1. Field of the Invention
The present invention relates to a complex system of vegetation and a solar cell in which a plant group having a heat island phenomenon suppression effect and a solar cell having a carbon dioxide generation suppression effect are installed together.
2. Description of the Related Art
Greenification, which involves planting plants on the roofs of structures such as buildings in order to suppress the heat island phenomenon of densely populated urban areas that has become a problem in recent years, is being implemented nowadays. Further, solar cells, which do not involve fossil fuels, that is, which constitute a power-generation technology with a low environmental load without involving the generation of carbon dioxide, have been put to practical use. As a method that installs plants and solar cells together, a method that installs plants on the roof of a building and solar cells on the walls thereof has been disclosed by Japanese Patent Application Laid Open No. 2002-364137, for example. Further, a method that installs plants on one side of a sloping roof and solar cells on the other side thereof has been disclosed by Japanese Patent Application Laid Open No. 2002-206349. However, even though the reception of solar light by plants and solar cells is a requirement for the production of the effect, these methods are installation methods in which at least the amount of light received in either case is small and an installation method that installs plants and solar cells together on substantially the same plane has not been proposed. It may be surmised that the problems of the effect of the shadows of the plants and solar cells as well as maintenance have not been resolved.
Furthermore, as mentioned in ‘Design and Execution of a solar light generation system (Second Edition)’ (editor: solar light generation association, published at Ohm Corp on Feb. 10, 2000) pages 115 to 116, the higher the building height, the greater the wind pressure acting on the solar cell system. For example, the wind pressure is proportional to the square root of the part of the height of the building not more than 16 meters and proportional to the fourth root of the height for the part exceeding 16 meters. Therefore, one may surmise that the method of fixing a solar cell system to a high-rise building is a factor in high costs.
A solar cell module is formed in the shape of a flat plate with a large surface area in order to adequately receive solar light. The solar cell module normally has a transparent glass plate on the surface thereof so that solar light adequately reaches an internal photoelectric conversion element and so as to be durable enough for outdoor installation. Therefore the large-area plate-like glass plate occupies much of the weight of the solar cell module and is fairly heavy. When the glass plate is damaged, a state arises where a multiplicity of sharp-edged pieces exists and care must be taken in handling same.
Methods that fix this kind of solar cell module to the surface of a roof have been developed conventionally. For example, Japanese Patent Application Laid Open No. H8-288532 discloses a method that installs a mount to the surface of a roof by driving an anchor into the surface of the roof and fixing the mount to the anchor, and then installs a solar cell module on the mount. However, in this method, the roof surface sustains damage as a result of driving the anchor into the roof surface and there is therefore the risk of a drop in long-term waterproofing properties. An object of the roof surface where the mount is installed is to prevent the invasion of rain water into the building. For example, the whole of the roof surface of a building has a structure with a waterproof layer consisting of waterproof asphalt and a waterproof sheet and so forth. In order to resolve this problem, Japanese Patent Application Laid Open No. 2000-017802 discloses a method for waterproofing the part in which the anchor is driven. However, there is then the problem of the costs and labor involved in the waterproofing. Hence, Japanese Patent Application Laid Open No. H9-070188 discloses a method that, instead of using this method of fixing by means of an anchor, performs fixing by fastening a concrete foundation to the roof surface via an adhesive and fixing a solar cell module to the concrete foundation. However, maintenance mainly for the purposes of waterproofing such as re-covering the waterproof sheet must be performed at regular intervals on the roof comprising the roof surface and there has been the problem that it is not possible to temporarily remove the solar cell system in the bonding that involves such bonding of the concrete foundation to the roof surface via the adhesive.
Further, because the solar cell module naturally exists at a high point around and below which people pass, for example, it is essential to prevent the solar cell module dropping to the area around the roof in the event of a typhoon or earthquake or the like. A method of fixing the mount to the roof surface by means of wires has been considered conventionally. In the case of this method, when it is assumed that a wind will blow up above the solar cell module and mount, because the mount is fixed to a flat roof, the direction in which the pull force on the wire acts must be more in the vertical direction than in the horizontal direction of the roof surface. In order to secure a vertical direction component for the wire pull force, the angle of attachment of the wire, taking the roof surface, that is, the installation surface, as the reference, must be an angle that is to a certain extent close to the perpendicular. On the other hand, with this method, it is possible to prevent the solar cell module dropping to the area around the roof surface. However, when the mount is fixed to the roof surface by means of wire, in order to render the attachment angle an angle that is close to the perpendicular, the position in which the wire is fixed cannot be spaced far from the mount and, therefore, ultimately, there is a need to erect an anchor bolt in the roof installation surface and the waterproof surface must be damaged. In addition, another problem with this method that has been cited is that, when the surface area of the mount is large, blow-up close to the center of the mount cannot be prevented by fixing only the periphery of the solar cell module by means of wire. Further, Japanese Examined utility model application publication No. S62-70454 discloses a method involving a structure in which a solar cell module is attached to a wire that is extended in the direction of the installation angle of the fixed mount. In this structure, the two ends of the wire are reliably tied to the main body of the mount and the solar cell module is attached in a state in which same can be locked to the extended wire. In this case, because the load of the wind pressure on the solar cell module is supported by the wire, a wire draw strength that is regularly high is required and slight fluctuations caused by the wind pressure load are unavoidable and there is a problem with long-term durability resulting from metal fatigue of the wire main body and attachment portion. Further, when the surface area of the mount increases, the above problems are exacerbated. Meanwhile, as disclosed in Japanese Patent (Kokai) Application No. H8-284351, in a structure installed on roof tiles, there is a structure in which a wire is reliably tied to an anchor bolt penetrating the installation surface and the mount is attached to the wire. In this case, there is a method that involves fixing leg portions attached to the mount to the roof surface by means of adhesive in order to prevent a rubbing movement by the mount caused by the wind and so forth. With this method, there is sometimes a problem with the waterproof structure of the penetration part due to the act of securing the mount attachment load by means of the anchor bolt that penetrates the roof surface via wire. Further, when the solar cell module is bonded after being fixed with wire, it is difficult to firmly and uniformly bond at all points and, when an excessive load is applied, there is the possibility of damage to weak points.